Smooth wear-resistant resilient floor covering and method of making same



March 21, 1967 R. K. PETRY 3,310,422

SMOOTH WEAR-RESISTANT RESILIENT FLOOR COVERING AND METHOD OF MAKING SAMEFiled July 1e, 1965 w R.T 2h MK. mm

United States Patent O Public 8 Claims. (Cl. 117-76).

' This application is a continuation-impart of my copendingfapplicationSer. No. 455,929, filedv May 14, 1965, now abandoned, which, in turn, isa continuation-in-part of U.S. application Ser. No. 276,607, filed Apr.29, 1963, which issued as United States Patent 3,239,365, which, inturn, is a continuation-impart of U.S. application Ser. No. 168,477,filed `Tan. 24, 1962,` now abandoned, which, inl turn, is acontinuation-in-part of U.S. application Ser. No. 841,409, led Sept. 2l,1959, now abandoned, and U.S. application Ser. No. 691,883, led Oct. 23,1957, now United States Patent 2,943,949.

This invention relatest'o flexible plastic surface coverings which havea decorative surface and particularly to such products having `aresilient cellular foam layer.

Printedproducts adaptable as decorative and protectivey coverings forfloors, walls andthe like have been available for many years. Thetechnique of printing on a flexible backing sheet with an oleoresinousenamel paint decoration has Ibeen used commercially for at least 40years to produce products commonly referred to as printed feltA base.Such products can be readily manufactured in a variety of attractivedesigns and are low in cost.

Printed felt base has a hard, smooth decorative wearing surface.Although this renders the product easily cleaned, the hard surface tendsto result in excessive noise from foot traffic. In addition, the hardsurface can cause fatigue to those who must stand for long periods oftime upon such products. The comfort and quietness of conventionalprinted felt base is somewhat better than ilo-ors of wood and stone dueto the cushioning characteristics of the felt backing, but since thefelt layer is very thin and on the back of the product, the improvementis only slight. Also, the thin product lacks any appreciable resistanceto the flow of heat with the result that printed felt base coveredfloors tend to be cold, an effect augmented by the smoothand `glossywearing surface.

Efforts have been directed toward improving the resilience of smoothsurface floor coverings -of which printed felt base is an example.Products with improved resilience can be made by the application of athin layer of foam rubber to the back of the surface covering. A1-though this does improve the properties of products such as printed feltbase, there are certain disadvantages. Foam rubber is subject todeterioration and chemical attack, particularly if it is installed upona concrete floor. The resulting breakdown of the cell structure causesthe product to lose its resilience.- Also, where products are to beadhesively bonded to a surface during installation, the adhesive canbecome at least partially absorbed into the foam cell structure withresultant loss of at least some of the effect of resilience.

A major source of competition for smooth surface floor coverings, suchas printed felt base, is from woven or tufted soft surface carpeting.Carpeting is not only soft and comfortable underfootA but also has athreedimensional textured appearance which is particularly attractive incertain areas in the home. Soft surface carpeting, although highlyattractive, has a serious ydisadvantage in that it readily soils andonce soiled it is diicult to clean.

ICC

In my United States Patent 2,943,949, issued July 5, 1960, there isdisclosed a product having a textured surface and the resiliency of softsurface covering such as tufted carpets while still retaining theunitary readily cleanable surface of printed felt base. This product isproduced by'coating' or printing a foa'rnable thermoplastic resinouscomposition on a textured backing' such as an embossed flooring felt andthereafter heating the foamable layer to fuse the resin and foam thethermoplastic cornposition. The result of this procedure is a surfacecovering having the three-dimensional appearance caused by the embossingbeing reproduced in reverse in the surface, a very resilient naturecaused by the foam to simulate carpet and the ease of cleaning attributeof printed felt base. This product can be coated with a resinousmaterial such as by spray coating to increase the service life of theproduct. The textured surface, however, makes iti diflicult to apply arelatively thick we'ar layer coating.

One of the most'dii'cultvproperties to impart in resinous compositionil-oor covering is good indent recovery. If a floor covering has poorindentrecovery, it quickly becomes covered with small concaveimpressions from heels' and!- thel like which causes rapid deteriorationin appearance. Substantial researchv effort has been directed toimproving indent recovery of such flooring.

An object of the invention is to produce a decorative surface coveringcharacterized by excellent indent recovery and comfort underfoot whilehaving increased `wear resistance. Another object of the invention is toprovide a process for producing such a product in a simple andeconomical manner. A further object of the inven` tion is to produce asurface covering with a resilient wearing surface of substantialthickness and which is relatively low in cost. Other objects and theadvantages of the invention will appear hereinafter.

In accordance with the invention, a surface covering having a solid wearlayer of substantial thickness, a cellular foam nterlayer and a backingwhich can be subsequently removed, if desired, is produced by coatingthe Ibacking with -a thermoplastic polymer composi-A tion contain-ing ablowing agent, applying a wear layer second coating of thermoplasticresinous composition' of substantial thickness over the first coatingthereby' completely covering the foamable coating Iand heating to fusethe resins and foam the coating to 'form a foamed structure having asolid, unfoamed surface Ilayer correspond-ing to the thickness of Itheapplied wear l-ayer. It is essential to this invention that thethickness and compositions of the foam layer and wear layer corne withindefined limits to give the product an acceptable cornbination of indentrecovery and cushioning. It has been discovered that the thickness ofthe foam layer must be from about 0.020 inch to about 0.100 inch with apreferredV range of about 0.030 inch to about 0.060 inch. The solidIwear layer must be at least 0.003 inch to about 0.025 inch andpreferably about 0.006 inch lto about 0.015 inch in thickness. Inaddition, the wear layer and backing must be of a .precise compositionand construction as hereinafter described. Further, it is desirable forthe invention that the wear layer composition is fused prior todecomposition of the blowing agent in order to form a smooth, solid wearlayer freeV of cells caused by gas migration. This canv be accomplishedby utilizing las the backing a felt sheet of substantial thickness atleast 0.010 inch. Such a felt sheet insulates the foam layer fr-om theheat during the fusionand blowing step. The insulation of the feltcauses the major portion of heat to pass through the surface of theproduct which results in the wear layer becoming fused prior to the foamlayer. It is surprisingthat the' wear layer of the product is freev fromgas cells. It would be expected that the' gas formed by thedecomposition of the blowing agent would migrate into the wear layer.This desirable result is accomplished by the critical nature of thebacking and the wear layer compositions and the heating procedure.

The invention will be better understood from the following detaileddescription of one embodiment of the invention when read in conjunctionwith the drawings wherein.

FIGURE l is a schematic representation of a method of producing one typeof surface covering in accordance with the present invention;

FIGURE 2 is an enlarged cross-sectional view of one type of texturedflexible backing for use in preparing products ofthe invention;

FIGURE 3 is an enlarged cross-sectional view of the backing of FIGURE 2with a coating composition applied thereto;

FIGURE 4 is an enlarged cross-sectional view of the coated backing ofFIGURE 3 having a printed design on its surface;

FIGURE 5 is an enlarged cross-sectional view of a three-dimensionalprinted surface covering produced by the method of FIGURE 1; and

FIGURE 6 is a portion of the surface of the surface covering shown inFIGURE 5.

With reference to FIGURE 1, a backing sheet 11, which can be of feltedfibrous backing material and embossed in one surface by passing throughan embossing unit, is passed to -a coating apparatus. The embossing unitcomprises an upper embossed roll 12 bearing a plurality of spacedprotuberances 13 which are provided in the pattern to be embossed in thesurface of the backing sheet. In the embossing unit, the felt sheet iscontacted by a back-up roll 14. The coating apparatus can comprise adoctor blade 18 which allows a uniform layer of resinous composition 19containing a blowing agent from reservoir 20 to be applied to thesurface of the felt as it passes beneath the blade. The coating lissuicient to ll the depressions 17, if present, and form a smoothsurface. The coated felt passes to an endless belt 22 provided with pins25 which project vertically from the belt at spaced poin-ts throughoutits length. The belt 22 passes around and is driven by wheels 23, 24.The 'web of backing lmaterial 15 is engaged by the pins 25 which piercethe side edges of the web and advance it along the machine. The coatedfelt is carried by the endless belt 22 to an oven 30 provided withinfrared heat lamps 31. The oven supplies sufficient heat to theresinous composition to gel or partially gel `the composition withoutdecomposing the blowing agent contained in the composition. The gelledcornposition which is a solid is then passed through a cooling chamber33. The cooled coated felt is then conveyed to -an apparatus forapplying an overall wear layer. The wear layer can be a transparent oropaque coating or it can be applied by printing to form a design as byusing a printing apparatus generally indicated at 40. The printing orcoating can be performed by any of the conventional coating or printingtechniques which will allow the application of a uniform layer ofsubstantial thickness. The printing apparatus as shown comprises twoprinting cylinders 41 and 42. A resinous composition which forms theprinting ink is supplied to the printing cylinders 41 and 42 fromreservoirs 43 and 44. As the printing cylinders revolve, portions of theprinting composition are picked up by lthe design elements engraved or`otherwise formed on the cylinders and placed on the coated felt. I Theprinting 45 and 46 has to be suicient to completely cover fthe coated1feilt to form a uniform coating. The printed sheet passes through anoven 51 in which the composition is fused and foamed, thereby producinga decorative yfoarned product 53 which, if an embossed base was used,bears a plurality of raised foamed portions which correspond in locationto the depressed portions inthe embossed felt backing. The

product has a solid resinous surface formed by the printed coatings 4Sand 46 and a resilient foam interlayer 19. The product is withdrawn fromthe oven and passed through a cooling chamber 55. The product can tbeused in sheet form as produced or can be cut up into tiles or otherappropriate shapes.

The operation of the printing step is conventional and in place of therotary method shown, a bloc-k printing machine or any other printingmethod can ,be used. As indicated alternately, a design can be printedon the surface of the gelled foamable coating such as with a rotogravureprinting press and conventional printing inks and then a transparent orcolored wear layer coating of substantial thickness is applied Iby meansIof reverse roll coater, doctor blade or the like coating apparatus.

If the backing is to be removed from the final product as an alternatemethod, the solid coating which will form the wear layer of the productcan Ibe first applied to the surface of the backing material. is thenheated .to gel the composition, a design 'can be printed on the gelledcoating and the foarnable coa-ting is applied to the surface of thegelled wear layer over the design. After fusing the two coatings andfoaming the composition, the product is stripped from the base andinverted for use. In such a procedure,- itis essen-tial to use a blowingagent which decomposes at a temperature substantially above the fusiontemperature of the wear layer.

The backing sheet is preferably a iiexible strong material which willremain part of the product although, yas indicated, backing materialscan be used which are subse-1 quently stripped .from the inal product,such as strippable coated release paper or the like. A paper having acoating such as disclosed in U.S. Patent 2,273,040 which issued on Feb.17, 1942, is particularly suitable as a release paper. If the backingremains, flexibility is important since the product is conventionallystored in closely wound rolls and must be capable of being rolled andunrolled without cracking or tearing. Strength is important in a backingin view of the strains to which the product is subjected when handledlboth during manufacture and immediately prior to installation.

It has been found that felted cellulose or asbestos yfibrous sheetsimpregnated with a water-resistant and strengthening saturant yielddesirable backing sheets for the production of products in accordancewith the inven-l tion since they are low in cost and yet are llexibleand strong. The sources of cellulose can include cotton or other rags,wood pulp, paper boxes or mixtures thereof in any proportion. Inaddition, fillers such as wood flour can be used. A slurry of `fibrousmaterial in water is formed into a sheet using any of the techniquesconventionally employed in the manufacture of paper. For example, sheetformulation can take place on a Fourd drinier or cylinder sheet-formingmachine. The fibrous sheet so prepared is then dried. In addition tocellulose Iand asbestos, other fibers can @be used including syntheticiibers and those of mineral and animal origin. lIt has been found that afelt sheet of at least 0.020 inch in thickness gives the Ibestinsulating properties.

The particular impregnant or saturant chosen must not only be capable ofimparting strength and water resistance to the sheet of felted bers, butmust also meet other requirements as to its physical and chemicalbehavior at the high processing temperatures. The coating compositionapplied to the backing in accordance with the invention must be heatedto temperatures -as high as 300 to 400 F. in order to fuse the resin andexpand the composition into a foam. Thus, the impregnant chosen must bestable at these temperatures. The impregnant should be substantiallyfree of any components which are Volatile -at these temperatures and italso must not soften to such an extent as to exude from the sheet. Inaddition, the saturant should not be subject to appreciable detrimentalchemical changes such as oxidation.

Suitable impregn-ants include vinyl resins, such Ias co;

The wear layer coating Y polymers of vinyl chloride, polymerized acrylicand methacrylic `acids and their polymerized derivatives, polyethylene,polystyrene, butadiene-styrene copolymer, butadiene-acrylonitrilecopolymer, natural rubber, pollymerized chloroprene and the like.'Ihermoset-ting resins which under the influence of heat cure bypolymerizing and cross-linking can also be used as impregnants. Suchresins as phenolic resins, polyesters, oleoresius such as drying oilsand the like, isocyanates and polyurethanes and the like are suitable.

Such resins can -be incorporated into a felted fibrous sheet byimpregnation of the finished sheet with an emulsion or solution of theresin followed by drying of the sheet to remove the solvent.Alternately, the resin can be added in fine particles to the fiberyfurnish prior to sheet formation either as soli-d particles of resin oras an emulsion in Water or other emulsifying vehicle.

Some resign impregnants which produce a felted sheet with excellentphysical properties are not compatible with the foarnable composition tovbe applied. This may result in poor adhesion of the foam to the base.-In such cases, it is desirable to size Ithe surface of the impregnated-felt sheet to which the foamable composition is to tbe applied with athin coating of material which has good adhesion to lboth the feltimpregna-nt and the foama'ble composition. :Where a plasticizerpolyvinyl chloride polymer foam is used excellent results have beenobtained over a wide variety of Ifelt impregnants using a size ofacrylic polymer latex. A mixture of equal parts of a soft acrylicpolymer l-atex and a hard acrylic polymer latex has been foundparticularly effective in aiding adhesion and fidelity of the texturedesign, without causing sticking of the sized surface to the rollsduring the processing The coating is effective in small amounts, anapplication of only 0.02 pounds dry weight per square yard beingsufficient to obtain the improvements. Other vinyl resins can also beused, depending upon the type of felt impregnant and foam appliedthereon. A butadieneacrylonitrile polymer latex either alone or incombination wit-h hard resin emulsions is effective.

The backing sheet in one of the embodiments has a texture in the form ofydepressed and raised portions in accordance with the particularthree-dimensional overall efect desired in the nished product. Thecontrast between the depressed and raised portions should be at least 5mils; that is, the depressed portions should lie at least 5 mils belowthe raised portions in the textured backing sheet. Where a backingnaturally bearing a smooth surface is used, thisl backing sheet can beembossed to produce the desired texture. Any of the conventionaltechniques of embossing such as fiat bed or rotary embossing can beused. Where a backing sheet in its natural state already possesses thedesired type and character of texture, no embossing is necessary. Coarsewoven fabrics possess natural texture and when they are used asbackings, the outline and effect of the weave is formed in the foamstructure in the finished product. Where other types ofthree-dimensional effects are desired in the finished product, it ispreferable to use a natural smooth backing sheet which is embossed inthe desired pat-tern. The embossing can be in any desired pattern, butthe best appearance is created by a uniform overall embossing, forexample, a series of evenly spaced depressions as illustrated in FIGURE2 or more elaborate embossing, if such an effect is desired. The shapeand position of the depressed areas in the backing will conform to theraised areas in the finished product. The deeper the embossing or-texture in the backing, the greater will be the three-dimensionaleffect in the product.

In accordance with the invention, a coatingV of foamable composition isapplied to the base and subsequently a second wear layer coat ofresinous composition is ap'- plied. The resinous binder must be one thatis coalesced or fused into a continuous film by the application of heat.The dispersion medium can be water in the case of an aqueous latex, oran organic solvent, but is preferably a fluid plasticizer for the resinused. Such a dispersion of resin in a plasticizer is -conventionallytermed a plastisol. A plas-tisol has appreciable fluidity at normal roomtemperature but is converted by heat into a flexible tough thermoplasticmass. This ultimate result is brought about by the process of fusionwherein the resin becomes plasticized and completely solvated by theplasticizer. Plastisols are preferred for the foamable composition sinceit is unnecessary to remove the carrier as is necessary with water andorganic solvent carriers. Organosols are preferred for the wear layersince they contain less plasticizer and are, therefore, less subject tostaining.

The preferred and most Widely used resins for surface coverings arepolymers of vinyl chloride. The vinylchloride polymers can either besimple, unmixed homopolymers of vinyl chloride or copolymers,terpolymers or the like thereof in which the essential polymericstructure of polyvinyl chloride is interspersed at intervalsk with theresidues of other e-thylenically unsaturated cornpounds polymerizedtherewith. The essential properties of the polymeric structure ofpolyvinyl chloride will be retained if not more than 40 percent of theextraneous comonomer is copolymerized therein. Suitable extraneouscomonomers include, for instance, vinyl esters on the order of vinylbromide, vinyl fluoride, vinyl acetate,

vinyl chloroacetate, vinyl butyrate, other fatty acid' vinyl esters,vinyl alkyl sulfona-tes, trichloroethylene and the like; vinyl etherssuch as vinyl ethyl ether, vinyl isopropyl ether, vinyl chloroethylether and the like; cyclic unsaturated compounds such as styrene, themonoand polychlorostyrenes, coumarone, indene, vinyl naphthalenes, vinylpyridines, vinyl pyrrole and the like; acrylic acid and its derivativessuch as ethyl acrylate, methyl methacrylate, ethyl methacrylate, ethylchloroacrylate, acrylonitrile, methacrylonitrile, diethyl maleate,diethyl fumarate and the like; vinylidene compounds on the order ofvinylidene chloride, vinylidene bromide, vinylidene fluorochloride andthe like; unsaturated hydrocarbons such as ethylene, propylene,isobutene and the like; allyl compounds such as allyl acetate, allylchloride, allyl ethyl ether and the like; and conjugated andcross-conjugated ethylenically unsaturated compounds such as butadiene,isoprene, chloroprene, 2,3-dimethylbutadiene-1,3-piperylene, divinylketone and the like. As a rule, the criterion of a practical comonomerfor use with vinyl chloride to produce copolymers containing percent ormore of vinyl chloride is that, on a mol percentage basis, an initialcharge of 96 percent Vinyl chloride, balance comonomer, shall yield aninitial copolymer containing (a) at least 90 percent vinyl chloride, and(b) not more than 99 percent vinyl chloride. On this basis, satisfactorycomonomers for use with vinyl chloride will be those having Q2 and e2values, as described in I. Polymer Science 2:101, correlated as follows,assuming for vinyl chloride Q vinyl chloride=0.03 and e vinylchloride=0.3.

Instead of the singleunsaturated comonomers of the types aboveindica-ted, mixtures of such comonomers may enter into the copolymers,it being understood that the total quantity thereof shall be smallenough that the essential character of the polyvinyl chloride chain isretained. Although such vinyl chloride resins are preferred, as isapparent, the coating composition can be formed from any resin which canbe gelled and foamed and the invention is not intended to be limited toany particular resin or group since many other types and groups ofresins will occur to -those skilled in the art.

Resins adaptable Ifor use in formulating vinyl plastisols are commonlyreferred to as ydispersion grade resins. Such resins are availablehaving particle sizes of from 0.02 to about 2 microns in contrast tocalender grade vinyl resins which are available in particles ranging upto 35 microns in size. Dispersion grade resins are usually of highermolecular weight than calender grade resins and have particle surfacesof a hard, horny nature.

Polymers of vinyl chloride having a specific viscosities above about0.17 and preferably between 0.17 and 0.31 as measured in a solution of0.2 gram of resin in 100 milliliters of nitrobenzene at 20 C. areparticularly effective. In the determination of specific viscosities,the sample of resin in nitrobenzene solution maintained at a temperatureof 20 C. is allowed to iiow between two calibrated marks in a pipetteand time required is recorded. This time is compared with the timerequired for a control of pure nitro'benzene solvent to pass between thesame two marks, also at a temperature of 20 C. The specific viscosity isdetermined as the sample ilow time, minus 1. The specific viscosity isan eifective measure of relative molecular weight of the polymer, thehigher the specific viscosity the higher being the molecular weight. Theintrinsic viscosity is another method `for determining molecular weight.Resins are preferred which have an intrinsic viscosity of from about0.75 to about 1.3. The intrinsic viscosity is obtained from viscositymea-surernents, at 30 C., of cyclohexanone solution of the resin and ofcyclohexanone solvent. The intrinsic viscosity [n] is deiined by theequation [11]:C lim-0 t lnfqrel.)

when nrel. is relative viscosity and C is the concentration of polymerin grams per 100 cc., the concentration being such that nrel. has avalue of from 1.15 to 1.4.

In the formulation of coating compositions for use in the invention, theresin is uniformly dispersed in a mass of fluid plasticizer in aplastisol or with plasticizer and organic solvent with an organosol. Thefluidity of plastisols is influenced in part by the particular resin:selected but is also a function of the ratio of plasticizer to resin.Plastisols become less fluid as the ratio of plasticizer to resin isreduced. Coating compositions for use in the invention contain fromabout 45 to about 80 parts plasticizer per 1.00 parts resin With a rangeof about 60 to about 70 parts plasticizer per 100 parts resin beingparticularly effective for the foamable coating. The plasticizer levelof the wear layer composition can be as low as 28 parts per 100 parts ofresin up to about 50 parts with 30 to 40 parts of plasticizer per 100parts of resin being preferred. The viscosity of the compositions can bereduced by the addition of a volatile diluent. Plastisols usuallycontain less than 10 parts per 100 parts resin of diluents. Usefuldiluents include benzene, toluene, methyl ethylketone, petroleumsolvents such as V., M. -and P. naphtha (boiling range of l90-275 F.)and the like. If the composition is to be applied by a printing step, itis usually applied as a plastisol which requires reducing its viscosity.Suitable printing compositions have a viscosity of 25 C. of from about200 to about 25,000 centipoises as measured with a Brookfield viscometerusing a No. 6 spindle at 10 r.p.m. For printing by the flat bedtechnique, a viscosity range of about 500 to about 5,000 centipoises isdesirable with a range of about 1,000 to about 3,500 centipoises beingparticularly effective.

The selection of the plasticizer is important in determining thestrength and flexibility of the coating and also in influencing theviscosity, stain resistance and the foaming characteristics |of thecomposition. Esters of straight and branched chain alcohols withaliphatic acids impart low viscosity and good viscosity stability.Typical plasticizers of this type include dibutyl sebacate, `dioctylsebacate, dioctyl adipate, didecyl adipate, dioctyl azelate, triethyleneglycol di(2ethylhexanoate) diethylene glycol dipelargonate, triethyleneglycol dicaprylate and the like. Plasticizers of the aromatic type, suchas esters of aliphatic alcohols and aromatic acids or aromatic alcoholsand aliphatic acids or aromatic alcohols and aromatic acids aredesirable in that they impart good foaming characteristics to aplastisol, although the use of highly aromatic plasticizers is limitedby their tendency to yield plastisols of high Viscosity. Typicalpiasticizers of this type include dibutyl phthalate, dicapryl phthalate,dioctyl phethalate, dibutoxy ethyl phthalate, dipropylene glycoldibenzoate, butyl benzyl sebacate, butyl benzyl phthalate, dibenzylsebacate, dibenzyl phthalate and the like. Other types of plasticizers,such as esters of inorganic acids, including tricresyl phosphate, octyldiphenyl phosphate and the like, alkyl derivatives of rosen, chlorinatedparain, high molecular weight hydrocarbon condensates and the like canalso be used. The plasticizer or blend of plasticizers is chosen toyield a composition of the desired viscosity and/or foamingcharacteristics. In addition, the plasticizer should preferably have alow vapor pressure at the temperatures required to fuse the resin. Avapor pressure of two millimeters of mercury or less at 400 F. issatisfactory.

Minor amounts of stabilizers are usually incorporated in the coatingcompositions to reduce the effects of degradation by light and heat.Suitable light stabilizers include resorcinol disalicylate, resorcinoldibenzoate, phenyl phthalate, phenyl benzoate, o-tolyl benzoate,eugenol, guaiacol, o-nitrophenol, o-nitraniline, triethylene glycolsalicylate, and organic phosphates and -other complexes of such metalsas barium, cadmium, strontium, lead, tin and the like. Suitable heatstabilizers include sulides and sultes of aluminum, silver, calcium,cadrnium, magnesium, cerium, sodium strontium and the like, glycerine,leucine, alanine, oand p-a-mino benzoic and -sulfanilic acids,hexarmethylene tetramine, weak acid radicals including oleates,recinoleates, abietates, salicylates and the like. Normally, thecompositions contain about 0.5 to about 5 parts stabilizer per 100 partsresin. Care should be exercised in the selection of a stabilizer sincesome types will catalyze the decomposition of the blowing agent whichwill alter the operating temperature.

The coating compositions can contain pigments in accordance with theparticular color desired. Where a multi-colored decorative effect iscreated in accordance with the invention by printing, separate batchesof printing composition for each of the colors desired are needed. Anyof the organic and inorganic pigments well known in the art forpigmenting compositions can be used. Normally, from about 0.5 to about 5parts pigments per 100 parts resin are used.

The foamable compositions contain, in addition, an effective amount ofblowing agent. The larger the amount of blowing agent Within practicallimits used the greater is the expansion of the foam. Foam densities offrom about l2 to about 40 pounds per cubic foot can be readily attained.Such results are attainable with from about 1 to about 20 parts blowingagent per 100 parts resin. About 2 to 10 parts blowing agent per 100parts resin is particularly effective for the production of foams and adensity which `are most desirable for use in producing surface coveringsin accordance with the invention. The amount of blowing agent willdepend in large measure on the eiciency of the agent. It has been foundthe blow ratio, i.e., the ratio of the thickness of the foam layer tothe thickness of the unblown layer, is critical and should be from about2 to about 5. If higher ratios are used, gas migration will take place.

Complex organic compounds which, when heated, decompose to yield aninert gas and have residues which are compatible with the resin used inthe `compositions are preferred as blowing agents. Such materials havethe property of decompositions over a narrow temperature range which isparticularly desirable for -obtaining a good foam structure. Compoundshaving the N-N and NIN- linkages decompose at elevated temperatures toyield a gas mixture high in nitrogen. Typical cornpounds includesubstituted nitroso compounds, substituted 9 hydrazides, substituted azocompounds and the like, such as are tabulated in Table 1:

` TABLE 1 Approximate decomposition Blowing agent: temperature, F.

Dinitrosopentamethylenetetramine 355-375 Azodiformarnide(NH2-C-N=N-C-NH2) S25-400 p,p-Oxybis (benzene sulfonyl hydrazi-de)300-340 Azobisisobutyronitrile 220-250N,N-dimethyl-N,N'-dinitrosoterephthalamide 190-300 The decompositiontemperature depends in large measure on the particular composition.Catalyst can be added to aid in the decomposition and change thetemperature range. Typical catalysts are the zinc and lead salts whichalso serve as stabilizers.

Blowing agents for use in the invention must be decomposed at aneffective rate at a temperature below the decomposition temperature ofthe resin used but above the elastomeric point of the resin composition.A layer of resinous foam has heat insulating properties with the resultthat fusion of a prefoamed layer is very difficult and extremely slow.Therefore, in the case of compositions formulated with the preferredvinyl chloride polymers, `a blowing agent decomposing between about 300and 450 F. should be used. The minimum initial decomposition temperaturemust be suiciently high that no premature gas evolution occurs duringmixing of the composition, coating operation, and particularly thegelling step. In the event the coating is to be fused before the wearlayer is applied, then it is necessary to use a blowing agent whichdecomposes above the fusion temperature of the resin. In general, vinylchloride polymer compositions attain body through partial gellation whenheated to about 200 F. Thus, the minimum decomposition temperatureshould be about 200 F. or higher.

After the rst coating is applied, the coating is heated to gel thecomposition.` In this specification and claims, the term gel includesboth the partial (at least the elastomericpoint) and complete solvationof the resin or resins with the plasticizer. The heating is limited asto the time and temperature to prevent the decomposition of the blowingagent in the composition. When using-the preferred polyvinyl chloridecomposition, the temperature of the composition is preferably raised toabout 240 F. to about 275 F. Generally, the oven temperature would beslightly higher temperature to have the coating reach the desiredVtemperature. After gelling the rst coat, the product is cooled.

The degree of foaming of a typical plastisol formulation usingVdifferent concentrations of blowing agent is shown in the Table 2:

Parts Azodifornl- Ratio of Foam Density, lbs. amide per 100 Thickness toper en. ft.

parts Resin Original Thickness It4 has been found that density of fromabout` 15 to 20 pounds per cubic foot produces the most useful products.

For the;product of this invention to be used asa surface covering, suchas oor covering, it is essential for the product to recover fromindentation or be substantially free from permanent indentation. Theproduct is considered to meet these requirements if the permanentindentation is less than 0.010 inch after seven days following theremoval of a load of 300 pounds per square inch applied with a 1A inchdiameter rod for a 72-hour period. This depth of permanent indentationwould include any indentation placed in the felt base, if present. Inorder for the product to have this quality, it is necessary to carefullybalance the thickness of the layers and the formulations of the foam andwear layers. It has been discovered that when utilizing the preferredfoam formulation of about 60 to about 70 parts of plasticizer per 100parts of resin, a product having an excellent combination of indentresistance and cushioning properties for both short and long durationtime of load is obtained with wear layers of from about 0.004 to about0.008 inch containing from 30 to 40 parts of plasticizer per 100 partsof resin when used with a foam thickness of from 0.04 to about 0.06inch.

The foam composition should fuse at a temperature at or below thetemperature at which the wear layer fuses. The wear layer compositionpreferably contains a polymer combination which has an average molecularweight greater than that in the foarnable coating. It has beendiscovered that the thickness of the solid composition is also critical.If the thickness is less than 0.003 inch, the gas from the lower coatingcan pass right through it thereby completely losing the desired solidsurface layer.

After gelling, the temperature of the composition should be reduced sothe wear layer coating composition will not be affected. After coolingand the application of the wear layer, the composition is heated to atemperature suflioient to fuse the resins in both layers and decomposethe blowing agent. The temperature of the e11- tire mass of compositionupon the backing must attain the fusion temperature of the resins inorder that a product of satisfactory strength can be attained. Inaddition, lthe entire mass of foamable composition lmust be heated to apoint where the blowing agent is decomposed. As indicated, the backingsheet serves to insulate the foamable composition from the heat so thatthe wear layer fuses prior to any substantial'decomposition of theblowing agent. The backing sheet should, therefore, have a thickness ofat least 0.010 inch. From a practical production standpoint, it isimpossible to prevent the application of heat to both surfaces of thesheet. Where a high temperature blowing agent is used, blowing does notoccur until the resinous compositions have been completely fused. It hasbeen found that the wear layer at the decomposition temperature of theblowing agent should have a tensile strength of at least one pound persquare inchl, and preferably at least 2 to 5 pounds per square mc Ifvolatile diluents are used to reduce the viscosity of the coatingcomposition, care must be taken that they are essentially completelyremoved from the film prior to fusion and foaming. If they are notremoved, poor cell structure and blister formation will result. Thisremoval can be accomplished by heating the composition at a temperaturesubstantially below the fusion temperature and minimum decompositiontemperature of the blowing agent for suicient time to remove thevolatile material. For example, if 5 percent of V., M. & P. Naphtha(boiling range l-275 F.) is used, heating at 300 F. for three minuteswill remove sufficient material so that fusion and foaming at 400 F.ican be accomplished with good cell structure and freedom from blisters.

Heating in order to effect fusion and foaming can be brought about underinfrared heat lamps as shown in the drawing or other types of heatingsuch as forced hot air oven or dielectric heating units can be used.

When the base is embossed, expansion of the coating due to foamingyields a three-dimensional textured effect which duplicates in reversethe texture in the backing.

That is, depressions in the backing appear as raised areas of foam. Thesize of the raised areas in the foam product depends on the depth of thedepressed areas in the backing and the amount of expansion in thefoaming process. The decorative design is unimpaired by the foaming, inthat the foa-med surface accurately reproduces the printed patternapplied. The decorative effect is enhanced by the three-dimensionaltexture present in the surface of the foamed product.

There are -certain limitations in reproducing the embossed felt designin the foam surface. Very fine and delicate embossings where the depthand width are less than about .005 inch are difhcult to reproduce withgood fidelity by this process. Similarly, embossings deeper than .050inch produce large texture effects in the foam surface and loss ofdetail. Embossings which have an average depth and width of from .015inch to 0.030 inch have given best results.

If the expansion of the foamable composition applied to the embossedfelt is too low, there will not be enough contrast between the high andlow areas to pr-oducea good textured effect. On the other hand, toogreat an expansion will result in a coarser foam structure which impairsdesign fidelity and too much lateral flow which depresses the design.For embossed felt depths of .015 inch to .030 inch, a foam expansion of300 percent to 600 percent can give good design fidelity. With thepreferred composition, a plasticized polyvinyl chloride foam, expansionsof 400 percent to 500 percent give the best combination of good designfidelity and foam structure.

The textured design is also affected by the total thickness of thef-oarn layer. In general, the foam thickness should be from 3 to 10times the average depth of felt embossing, but this is largely dependentupon dthe design selected. For the preferred embossing depths of from0.015 inch to 0.030 inch, the foam thickness should not exceed 0.100inch and 0.030 inch to 0.050 inch is preferred.

In order that the texture of the backing be accurately reproduced in thefoamed product, it is important thatY the coating iiow into and fill allthe depressions in the textured backing and become completely level soas to have a smooth surface prior to printing and foaming. In certaininstances, it is desirable to first fill the impressions and then applya second coating to the desired thickness. This latter system greatlyaids the leveling of the top coating.

The foamed and fused product after leaving the heating oven is permittedto cool. Cooling is particularly important since any premature handlingof the product immediately after foaming might cause partial collapseand distortion of the foam structure- Cooling can be brought about bymere exposure of the product to the atmosphere; thus, the speed ofmoti-on of the backing along the proc-I essing apparatus can be adjustedso that the product is given sufficient time to cool. Alternately,cooling can be accelerated by blowing jets of -cooled air upon the fusedand foamed composition or by means of fine sprays of water upon thefused and foamed composition.

After being cooled, the product is withdrawn from the processingapparatus. It can be used in the form of a sheet as produced or can becut into tiles or other appropriate shapes depending on the particularuse to which the product is to be put. Products produced in accordancewith the invention have the characteristics of excellent wear and soilresistance because of the solid layer and excellent resiliency in viewof the foamed layer. In one form, they are also characterized by havinga marked three-dimensional textured appearance conforming to the textureof the backing. Still further, the products of the invention have goodheat insulating properties by virtue of the layer of foamed compositionand thus are warmer in winter and cooler in summer than conventionalsmooth surface coverings of the prior art.

Table 3 gives the preferred temperature and time rela-y tionship usingthe preferred polyvinyl chloride resin:

1 0.014 inch plastisol on 0.25 inch cellulosic felt base impregnatedwith 20% vinyl acetate and 10% petroleum hydrocarbon.

The time required to reach the elastomeric point will depend in part onthe film thickness and particular base as shown in Table 4:

TABLE 4 Base Film Thickness Time/Temperature (inch) (second/ F.)

1 Base A is a cellulosic felt of 0.025 inch thickness impregnated with30 percent vinyl acetate homopolymer.

2 Base B is a cellulosc felt of 0.043 inch thickness impregnated withsynthetic rubber and ureafformaldehyde.

The following examples are given for purposes of illustration:

Examples I to VII are typical foamable compositions:

Example I A foamable plastisol was formulated by grinding the followingingredients on a conventional three-roll mill:

Parts Vinyl chloride-vinyl acetate copolymer (dispersion grade) Dioctylphthalate 30 Dipropylene glycol dibenzoate 30 Stabilizer 6 Finelydivided titanium dioxide 2.5 Azodiformamide blowing ragent 2.5

The plastisol had a viscosity of 16,800 centipoises at 25 C. as measuredwith a Brookfield viscometer using la No. 6 spindle at 10 r.p.m. Thisplastisol can be pigmented as desired.

Example Il The following ingredients in the proportions indicated wereground on a three-roll mill:

Parts Polyvinyl chloride (dispersion grade) 100 Petroleum hydrocaroncondensate 18 Butyl benzyl phthalate 52 Pigment 3 Stabilizers 4Azodiformamide blowing agent- 3.5

t Conoco 30G-Continental Oil Company, Ponca. City, Okla.

The plastisol had a viscosity of 4,000 centipoises as measuredwith aBrookfield Viscometer using a No. 6 spindle at 10 r.p.m.

13 Example III The following ingredients were ground on a three-rollmill:

'Parts Polyvinyl chloride (dispersion grade) 100 Petroleum hydrocarboncondensate 18 Butyl benzyl phthalate 52 Pigment 3 Stabilizers 4Azodiformamide blowing agent 1 V., M. and P. Naphtha (boiling range lConoco SOO-Continental Oil Company.

The plastisol had a viscosity of 2,000 centipoises as measured with aBrookeld viscometer using a No. 6 spindle at 10 r.p.m.

Example IV Parts Polyvinyl chloride (dispersion grade) 100 Didecylphthalate 80 Stabilizers Pigment 2 Wetting agent 3.5

N,Ndimethyl-N,N'-dinitroso terephthalamide blowing agent 5 The plastisolwas prepared on a three-roll mill.

Example V The following ingredients in the proportions indicated wereground on a three-roll mill:

Parts Polyvinyl chloride (dispersion grade) 100 Didecyl phthalate 50Didecyl adipate 25 Stabilizer 5 Pigment 2 Wetting agent 3.5N,Ndimethyl-N,Ndinitroso terephthalamide blowing agent 5 Example VI Thefollowing ingredients in the proportions indicated were ground on athree-ro-ll mill:

Parts Polyvinyl chloride (dispersion grade) 100 Petroleum hydrocarboncondensate 18 Butyl benzyl phthalate 52 Pigment 3 Stabilizers 4Azodiformamide blowing agent 4.5

*Conoco BOO-Continental OilV Company.

The plastisol had a viscosity of 4,000 centipoises as measured with aBrookfield viscometer using a No. 6 spindle at r.p.m.

Example VII A foamable plastisol was prepared having the followingcomposition:

Parts Polyvinyl chloride (high .molecular weight) 100 Polyvinyl chloride(low molecular weight) 100 Azodiformamide 3 `Pigment (TiO2) 7 Dibasiclead phosphite 7 Butyl benzyl phthalate 100 The plastisol had aBrookiield viscosity of 6,400 (2 r.p.m., No. 3spindle).

Examplesv VII-Iv to XIV are typical wear layer compositions.

1 4 Example VIII The following ingredients in the proportions indicatedwene ground on a three-roll mill:

Parts Polyvinyl chloride (dispersion grade) Di(2ethylhexyl)hexahydrophthalate 50 Epoxidized soya oil 5 Wetting agent 2 Stabilizer 3Pigment 3 The plastisol had a viscosity of 2,500 centipoises as measuredwith a Brookfield viscometer using a No. 6 spindle at l0 rpm. It wassuitable for coating orV printingr. by the flat bed method.

Example IX The following ingredients in the proportions indicated wereground on a three-roll mill:

Parts Polyvinyl chloride (dispersion grade) 100 Petroleum hydrocarboncondensate 13 Butyl benzyl phthalate 37 Pigment 3 Stabilizers 4 ConocoSOO-Continental 0i1 Company.

The plastisol was suitable for coating or printing by the llat bedmethod.

Example X The following ingredients in the proportions indicated wereground on a three-roll mill:

e" Exon 654Firestone Plastics Co., Pottstown, Pa. Relative viscosity of2.65 (1% in cyclohexenone). 1

r* Exon G50-Firestone Plastics Co. Relative viscosity of 2.30 (1% incyclohexenone).

M* Conoco H-300-Continenta1 Oil Co., Ponca City, Okla.

The plastisol Was suitable for coating or printing by the Hat bedmethod.

Example XI A transparent organosol was prepared by mixing the followingingredients: Y

Parts Vinyl chloride polymer (dispersion grade) 100 Dioctyl phthalate1-6 Tricresyl phosphate 8.5 Polyester plasticizer 8.5 Stabilizer 4.0Mineral spirits 24 The organosol had a Brookield viscosity of 8,000 (2r.p.m.-No. 3 spindle).

Example XII Parts Polyvinyl chloride (dispersion grade) 100 Butyl benzylphthalate 43.7

Alkyl aryl hydrocarbon 4.4 Barium-zinc complex 3.5 Titanium dioxide (58%nely divided TiOZ i-n dioctyl phthalate) 3.0 Hydrocarbon diluent 4.4

Stormer Viscosity is 55 seconds per 100 rev. at 77 F. under 200 gm.load. Suitable for :application using the liat lbed printing technique.

l Example XIII A transparent organosol was prepared by mixing thefollowing ingredients:

Parts Polyvinyl chloride (dispersion grade) 100 Dioctyl phthalateTricresyl phosphate 15 Petroleum mineral spirits Methyl ethyl ketone 2Stabilizer 5 Example XIV A transparent organosol was prepared by mixingthe following ingredients:

A size coat is prepared having the following formulation:

Parts Polyvinyl chloride latex (preplasticized) 53 Carboxy vinyl polymer(thickener 2% in water) 35 Water 12 Ammonia to raise pH to 7-8.

Example XVI A sheet of felted cellulose fibers (.045 inch thick) wasproduced containing percent by weight of the fibers of polyvinyl acetatedispersed in fine particulate form at junctions of fibers within thesheet. The size coat of Example XV was applied to the surface of thesheet at a thickness of about 0.001 inch and dried. The sized surface ofthe sheet was embossed to a depth of 0.020 inch in a plurality of evenlyspaced depressions. The foamable plastisol composition of Example II wascoated on the surface of the embossed sheet by means of a doctor bladeto form a coating having a thickness of 0.010 inch. The depth of coatingover one of the embossed areas was, therefore, 0.030 inch thick. Thecoating was then subjected to heat at 375 F. for a period of fifteenseconds to gel the coating without decomposing the blowing agent. Afour-color pattern w-as printed by conventional block printing techniqueon a surface of the coated felt sheet. A film having a thickness of 15mils was printed and leveled. The printing composition was made inaccordance with Example VIII. The sheet was then passed through an ovenmaintained at 400 F. with a residence time of three minutes, therebyfusing the resin and expanding and foaming the -composition to produce afoamed product. The foamable composition expanded to yield a producthaving a minimum foam thickness of about 60 mils with a plurality ofraised areas conforming in location to the embossed depressions in thebacking. The surface of the product had a solid vinyl cornposition of`about 15 mils thickness free 0f any gas or foam areas. The product hasa four-color block-printed design with a three-dimensional texturedappearance and fthe presence of the foam composition results in a lsoftand resilient feel to the product underfoot.

Example XVII A sheet of felted cellulose fibers having a thickness of0.045 inch containing 25 percent by weight of the fibers of polyvinylacetate dispersed in fine particulate form at junctions of fibers Withinthe sheet. The sheet was embossed to a depth of 0.010 inch to provide aplurality of evenly spaced depressions in the surface of the felt. Thefoamable plastisol composition of Example VI was pre- 7^16 pared andpigmented lin a neutral color. The plastisol composition of Example IXwas prepared in four separate batches, each pigmented a different colorin accordance with the colors desired in the finished product. The

plastisol of Example VI was coated by means of a doctor blade over thesurface of the felt bearing the depressions in such a Way that thecomposition completely filled the depressions and gave a uniform coatingof 0.005 inch. The coated sheet was then heated to a temperature of 300F. for ninety seconds to gel the coating without decomposing the blowingagent. The four pigmented batches of the plastisol composition ofExample IX were used as printing compositions in printing a four-colorpattern by conventional block printing technique on the surface of thefelt bearing the depressions filled with the pigmented plastisol ofExample VI. A printed film having a thickness of 8 mils was produced.The printed film had a smooth and level surface. The sheet was thenpassed through an oven at 400 F. for three minutes, thereby fusing thepolyvinyl chloride in the plastisols and decomposing the blowing agentto foam the plastisol composition. The product bore a layer of foam overthe raised unembossed areas of the felt having a maximum thickness ofabout 40 mils with a plurality of raised areas conforming to theembossed depressions in the backing. The entire surface of the producthad a solid vinyl composition layer of about 0.008 inch in thickness.The finished product has a four-color, block-printed design with ahighly textured surface as a result of the raised foamed areas. Thepresence of the foam imparts a high degree of resiliency to the product.

Example XVIII A sheet of felted cellulose fibers having a thickness of0.045 inch containing 25 percent by weight of the fibers of polyvinylacetate dispersed in fine particulate form at junctions of fibers withinthe sheet. The sheet was ernbossed to a depth of 0.010 inch to provide aplurality of evenly spaced depressions in the surface of the felt. Fourbatches of the foamable plastisol composition of Example III wereprepared and pigmented in different colors. The plastisol composition ofExample XII was prepared in four separate batches, each pigmented thesame color as the foamable composition in accordance with the colorsdesired in the finished product. The four plastisols of Example III wereprinted by the fiat bed technique to form an overall four-color designhaving a minimum thickness of 0.005 inch. The printed design was thenheated to gel at 300 F. for 90 seconds. The four pigmented lbatches ofthe plastisol composition of Example XII were used as printingcompositions in printing a duplicate fourcolor pattern in register withthe first printed design by conventional block printing technique. Aprinted film having a thickness of 8 mils was produced. The printed filmhad a smooth and level surface. The sheet was then passed through anoven at 400 F. for three minutes thereby fusing the polyvinyl chloridein the plastisol compositions and decomposing the foaming agent toexpand the foamable layer. The product bore a layer of foam over theraised unembossed areas of the felt having a maximum thickness of aboutl5 mils with a plurality of raised areas conforming to the embosseddepressions in the backing. The entire surface of the product had asolid vinyl composition layer of about 0.008 inch in thickness.

` Example XIX A `first 4plastisol composition is formulated by mixingthe following ingredients on a conventional Cowles mixer:

Parts Vinyl chloride-vinyl acetate copolymer (dispersion inch thickness.

The plastisol of Example I is applied as a uniform coating of about0.008 inch in thickness on the surface of a release paper. The releasepaper has a coating of a complex compound of t-he Werner ytype in whicha trivalent nuclear chromium atom is coordinated with an acryliccarboxylic acido group having at least carbon atoms. Such a compositionis disclosed in United States Patent 2,273,040, issued Feb. 17, 1942.The plastisol coating is then heated to a 'temperature of 300 F. for 1minute to gel the composition. The gelled coating is then cooled. Thefirst plastisol composition is then coated on the surface of thecooled,gelled coating tomforrn a uniform coating of 0.005 inch in thickness.`The coatings are then heated to a temperature of 400 F. for a period of2 min- 4utes to fuse the compositions and completely decompose theyblowing agent to form a foam layer of 0.040 inch thickness integrallybonded to the wear layer of 0.005 The fused and foamed product is thencooled and the release paper is stripped from the back of the product.The resulting product has a foam underlayer with a solid resinous wearlayer integrally bonded thereto.

Example XX A foamable plastisol is formulated by' grinding the followingingredients on a conventional Cowles mixer.

. Parts Vinyl chloride-vinyl acetate copolymer (dispersion grade) 100Dioctyl phthalate 60 Alkyl aryl hydrocarbon 5 Dibasic lead phosphite lFinely divided titanium dioxide 2 Azodicarbonamide 4 The plastisol has aviscosity of 2,500 centipoises at 25 C. as measured with a BrookfieldViscorneter using a No. 6 spindle at 10 rpm. The plastisol is applied asa uniform coating of 0.008 inch on the surface of a 0.025 inch thickcellulose felt sheet impregnated with 9 percent vinyl acetate and 30percent hydrocarbon resin. The felt sheet had previously been coatedwith the size coating of Example XV at the rate of 0.025 pounds persquare yard and dried. The plastisol coating is then heated to atemperature of 310 F. for a period of 50 seconds to obtain a compositiontemperature of 250 F. thereby gelling the coating into a lm having anelongation of 100 percent. The organosol composition of EX- ample XI wasapplied to the surface to form a uniform coating of 0.004 inch inthickness. The sheet was then passed through an oven which graduallyraised the temperature of the coating to 400 F. The foamable coating andthe organosol coating fused and the blowing agent decomposed to form aproduct having a foam layer of 0.055 inch in thickness and a solid layerof 0.004 inch in thickness. The product made an excellent floor coveringhaving high wear :and stain resistance and excellent indent recovery.

Example XXI A foamable plastisol is prepared according to Example VII.The plastisol had a Brookfield viscosity of 6,400 at 25 C. using a No. 3spindle at 2 r.p.m. The plastisol was applied as a uniform layer of0.008 inch in thickness on the surface of a felt sheet 0.045 inch inthickness. The felt sheetwas composed of cellulosic fibers impregnatedwith 5% of a urea-formaldehyde resin and 25% of a copolymer ofbutadiene-acrylonitrile. The sheet had been heated to cure theurea-formaldehyde resin. The felt sheet had previously been coated withthe size coating of Example XV at the rate of 0.025 pounds per squareyard followed by drying the size coat. The plastisol-coated felt wasthen passed 'through an oven heated at 300 F. at the rate of 60 ft. perminute. The oven was 90 ft. long. The sheet was then allowed to cool and`fed to a conventional rotogravure printing machine which applied adecoration on the surface of the sheet with conventional vinyl printinginks. Because of the soft surface of the gelled foamable coating,excellent fidelity of print was obtained. The printed sheet was thenpassed to a reverse roll coater where an organosol coating of 0.005 inchin thickness was applied having the composition of Example XI. The sheetwas vpassed from the coater at a speed of 30 ft. per minute into an ovenhaving three zones each of 30 ft. in length. The zones were heated to325 F., 425 F., and 425 F., respectively. During this vheatingoperation, the compositions became fused and the blowing agentdecomposed to foam the foamable layer to al thickness of 0.032 inch. Theproduct wasrthen cooled and wound on a collecting roll. The productcould `be utilized directly as a oor covering having excellent indentrecovery. The solid transparent wear layer of 0.005 inch in thicknesshad excellent resistance to wear and staining and the design printed orithe surface of the foamable composition was clearly visible through thetransparent wear layer.

The product showed instantaneous recovery from spike heel shoes.|Utilizing an Armstrong indent tester with a 15/16 inch diam-eter domeof silence type pin with 100 lbs. of dead load for 60 secon-ds dwell,90% recovery showed within 60 seconds and 100% recovery within 10minutes. A long term indent test utilizing 3 inch diameter domes ofsilence with 112 and 224 lbs. per square inch for 9 days dwell showedcomplete recovery in one day for the lesser weight and approximatelyrecovery in one week for the higher weight.

lAny departure from the foregoing description which conforms to thepresent invention is intended to be included within the scope of theclaims.

What is claimed is:

1. A method of producing a resilient decorative surface covering havinga smooth, continuous resinous upper layer of uniform thicknesssubstantially free of any cellular structure bonded to a resilient foamlayer which comprises applying a uniform rst coating of a thermoplasticvinyl resinous composition containing an effective amount of adecomposable blowing agent to a smooth surface of a fibrous felt backingsheet having a thickness of at least 0.010 inch, heating to gel said rstcoating without decomposing the blowing agent, applying a uniform secondcoating of a thermoplastic vinyl resinous composition of at least 0.003inch in thickness to cover said lirst coating, said second coatinghaving a fusion temperature not lower than the fusion temperature ofsaid iirst coating and having a tensile strength of at least one poundper square inch at the decomposition temperature of said blowing agentand said blowing agent decomposes at a temperature above the fusiontemperature of the second coating composition, heating said rst andsecond coatings .to fuse the resin composition in the second coating,then continuing the heating to decompose the blowing agent and fuse saidfirst coating, and thereafter cooling the surface covering thusproduced.

2. The process of claim 1 wherein the thickness of the foam layer isabout tlwo to about five times the thickness of the original layer priorto decomposition of the Iblowing agent.

3. The process of claim 2 wherein said thermoplastic compositions arepolyvinyl chloride compositions.

4. The process of claim 2 wherein said brous felt .backing sheet has athickness of at least 0.020 inch.

5. The process of claim 2 wherein said second coating has a tensilestrength of from .three to about live pounds per square inch at thedecomposition temperature of said blowing agent.

6. A resilient decorative surface covering which comprises a feltedbrous backing sheet of at least 0.010 inch in thickness having a smoothupper surface, a layer of expanded and foamed plasticized thermoplasticvinyl resinous composition containing the decomposition products of ablowing agent and of uniform thickness covering said upper surface ofsaid backing sheet and a solid layer of plasticized thermoplastic vinylresinous composition of uniform thickness substantially free of anycellular structure of at least 0.003 inch bonded to the opposite surfaceof said foam layer, said solid layer of composition having a tensilestrength of at least one pound per square inch at the decompositiontemperature of said blowing agent, said expanded layer containing about45 to about 80 parts of plasticizer per 100 parts of vinyl resin andsaid solid layer containing from about 28 to about 50 parts ofplasticiZ/er per 100 parts of resin.

'7. A resilient decorative surface covering which cornprises a feltedrlilbrous backing having a thickness of at least 0.020 inch and a smoothupper surface, a thin vinyl resin size coat covering said upper surfaceof said backing, a layer of expanded and foamed plasticizedthermoplastic vinyl resinous composition containing the decompositionproducts of a blowing agent and having a thickness of from about 0.020to about 0.100 inch covering said upper surface of said backing sheetand a solid layer of plasticized thermoplastic vinyl resinouscomposition substantially free of any cellular structure bonded to theopposite surface of said foamed layer, said expanded layer containingabout 45 to about 80 parts of plasticizer per 100 parts of vinyl resin,said solid layer containing from about 28 to about 50 parts ofplasticizer per 100 parts of resin and said solid layer having a tensilestrength of at least one pound per square inch at the decompositiontemperature of said blowing agent.

8. A resilient decorative surface covering which cornprises a feltedfibrous backing having a thickness of at least 0.020 inch and a smoothupper surface, a thin vinyl resin size coat covering said upper surfaceof said backing, a layer of expanded and foamed plasticizedthermoplastic vinyl resinous composition containing the decompositionproducts of a blowing agent and having a thickness of from about 0.020to about 0.100 inch covering said upper surface of said backing sheetand a solid layer of plasticized thermoplastic vinyl resinouscomposition substantialy free of any cellular structure bonded to ltheopposite surface of said foamed layer, said expanded layer containingabout to about 80 parts of plasticizer per parts of vinyl resin, saidsolid layer containing from about 28 to about 50 parts of plasticizerper 100 parts of resin and said solid layer having a tensile strength ofabout 2 to about 5 pounds per square inch at the decompositiontemperature of said blowing agent.

References Cited by the Examiner UNITED STATES PATENTS 2,837,440 6/1958Boivin 117-11X 2,918,702 12/ 1959 Wetterau .264-47 WILLIAM D. MARTIN,Primary Examiner.

MURRAY KATZ, Examiner.

R. HUSACK, Assistant Examiner.

1. A METHOD OF PRODUCING A RESILIENT DECORATIVE SURFACE COVERING HAVINGA SMOOTH, CONTINOUS RESINOUS UPPER LAYER OF UNIFORM THICKNESSSUBSTANTIALLY FREE OF ANY CELLULAR STRUCTURE BONDED TO A RESILIENT FOAMLAYER WHICH COMPRISES APPLYING A UNIFORM FIRST COATING OF ATHERMOPLASTIC VINYL RESINOUS COMPOSITION CONTAINING AN EFFECTIVE AMOUNTOF A DECOMPOSABLE BLOWING AGENT TO A SMOOTH SURFACE OF A FIBRUOUS FELTBACKING SHEET HAVING A THICKNESS OF AT LEAST 0.010 INCH, HEATING TO GELSAID FIRST COATING WITHOUT DECOMPSOING THE BLOWING AGENT, APPLYING AUNIFORM SECOND COATING OF A THERMOPLASTIC VINYL RESINOUS COMPOSITION OFAT LEAST 0.003 INCH IN THICKNESS TO COVER SAID FIRST COATING, SAIDSECOND COATING HAVING A FUSION TEMPERATURE NOT LOWER THAN THE FUSIONTEMPERATURE OF SAID FIRST COATING AND HAVING A TENSILE STRENGTH OF ATLEAST ONE POUND PER SQUARE INCH AT THE DECOMPOSITION TEMPERATURE OF SAIDBLOWING AGENT AND SAID BLOWING AGENT DECOMPSES AT A TEMPERATURE ABOVETHE FUSION TEMPERATURE OF THE SECOND COATING COMPOSITION, HEATING SAIDFIRST AND SECOND COATINGS TO FUES THE RESIN COMPOSITION IN THE SECONDCOATING, THEN CONTINUING THE HEATING TO DECOMPOSE THE BLOWING AGENT ANDFUSE SAID FIRST COATING, AND THEREAFTER COOLING THE SURFACE COVERINGTHUS PRODUCED.